1. Field of the Invention
The present invention relates to a phase adjuster, a phase adjusting method and a display device which are suitably applied to a display device for displaying a video signal having a discrete picture element structure such as the video output of a computer.
2. Description of the Related Art
Conventionally, there are display devices such as an LCD (Liquid Crystal Display) or a PDP (Plasma Display Panel), etc., known as a display device to display a picture image based on a picture image signal having the discrete picture element structure outputted from a computer.
In such display devices, normally values such as sizes of H (horizontal) and V (vertical) or shifts of H and V which meet a typical signal standard of a VGA (Video Graphics Array) signal or an SVGA (Super VGA) signal or the like, have been previously stored in a storing means such as a memory. At the time of operation, the types of the inputted picture image signals are discriminated based on the polarities and frequencies of H synchronizing signals and V synchronizing signals, and the values of sizes of H and V or the values of shifts of H and V corresponding to said signal are read out. Then, the same number of clocks as that of the total number of picture elements on one H line, are generated based on said read values such as sizes of H and V, shifts of H and V. Thereby, the picture image of proper size can be displayed at a proper position based on the picture image signal by employing the above described clocks.
However, the amount of delay between a horizontal synchronizing signal and a picture image signal which are outputted from a computer, always changes depending on respective computers. Therefore, in the display device mentioned above, confirming visually the displayed picture image every time the computer is connected to the display device, a user needs to match the clock in the display device to the phase of an inputted picture element so that a picture image should be most clearly displayed.
Further, according to the conventional display device, a phase adjustment can be shifted due to the difference in temperature characteristic for the amount of delay of a picture signal system circuit and a horizontal synchronizing signal system circuit. Therefore, the phase is needed to be adjusted every time of the shift of the phase adjustment, so that the manageability or handiness of the conventional display device is undesirably problematical.
In view of the foregoing, an object of this invention is to provide a phase adjuster, a phase adjusting method and a display device by which the manageability or handiness can be extremely improved.
According to the present invention, there is provided a phase adjuster for adjusting the phase of the picture image signal of a picture image displayed on a display screen based on the same number of clocks as that of picture elements on said horizontal line generated on each horizontal line of the display screen, the phase adjuster comprising: counting means for counting the number of clocks between two predetermined picture elements of the picture image on an arbitrary horizontal line over a plurality of frames; and phase adjusting means for adjusting the phase of said clock so as to be corresponded to the phase of the picture image signal based on the counted result of said counting means. Thus, since the phase of clock can be always adjusted so as to most clearly display the picture image based on the picture image signal, the phase adjuster by which the manageability or handiness can be extremely improved can be realized.
According to the present invention, there is also provided a phase adjusting method for adjusting the phase of the picture image signal of a picture image shown on a display screen based on the same number of clocks as that of picture elements on the horizontal line generated on each horizontal line of the display screen; the phase adjusting method comprising: steps of counting the number of clocks between two predetermined picture elements of the picture image on an arbitrary horizontal line over a plurality of frames; and then adjusting the phase of said clock so as to be corresponded to the phase of the picture image signal based on the counted result. Thus, since the phase of clock can be always adjusted so as to most clearly display the picture image based on the picture image signal, the phase adjusting method by which the manageability or handiness can be extremely improved can be realized.
According to the present invention, there is further provided a display device for displaying on a display screen a picture image in accordance with a picture image signal whose phase is adjusted based on the same number of clocks as that of picture elements on the horizontal line generated on each horizontal line of the display screen, the display device comprising: counting means for counting the number of clocks between two predetermined picture elements of the picture image on an arbitrary horizontal line over a plurality of frames; and phase adjusting means for adjusting the phase of the clock so as to be corresponded to the phase of the picture image signal based on the counted result of said counting means. Thus, since the phase of clock can be always adjusted so as to most clearly display the picture image based on the picture image signal, the display device by which the manageability or handiness can be extremely improved can be realized.
As a result, even when the amount of delay between an externally inputted picture image signal and a horizontal synchronizing signal differs respectively depending on the kinds of externally inputting means, the phase of the clock can always be adjusted so as to most clearly display the picture image based on the picture image signal.